Cook jumbo shells according to package directions. Drain and run under cold water. Set aside.
In a large bowl, combine ricotta, 1 1/2 cups mozzarella, 1/2 cup parmesan cheese, eggs, salt, pepper, garlic powder, Italian seasoning, herbs, and spinach. Mix until well-combined.
Stuff mixture into shells evenly with a spoon or a cookie drop. Close the shells slightly.
Spread a thin layer of marinara sauce on a 9x13 inch baking pan. Place prepared pasta shells on baking pan, open side up, and each pasta shell close to each other.
Spread remaining sauce over the shells, and use a spatula to even out sauce. Sprinkle with remaining 2 cups mozzarella and 1/2 cup parmesan cheese. Note: if you want it extra cheese, just add more cheese to your liking!
Bake for 25 minutes, covered with aluminum foil. Remove foil and bake for 5 more minutes. Then broil for 3-5 minutes on high, until golden brown and bubbling. Let stand for 10 minutes. Enjoy!
You can remove excess water from the spinach by squeezing it with your hands or through cheese cloth, or pressing it through a sieve.